Role of stable eignmodes in 3D ETG-driven turbulence

The role of stable eigenmodes in Electron-Temperature-Gradient driven (ETG) turbulence is investigated. Low-wavenumber stable eigenmodes are thought to play a role in the dissipation mechanism leading to saturation of CTEM[1] and ITG[2] turbulence. Evidence has been found that the formation of magnetic coherent structures and the transition to a turbulence regime with stronger magnetic fluctuations are dependent of the ETG low $k$ stable modes in 2D fixed-$k_z$ fluid simulations[3]. A 3D code has been constructed to investigate the role of stable modes in 3D sheared slab geometry. Magnetic structure formation and electromagnetic ETG turbulence will be discussed in detail. [1] P.~W. Terry, D.~A. Baver and S.~Gupta, Phys. Plasmas \textbf{13}, 022307 (2006). [2] R.~Gatto, P.~W. Terry and D.~A. Baver, Phys. Plasmas 13 022306 (2006). [3] J.-H. Kim and P.~W. Terry (2008), 50th Annual Meeting of the Division of Plasma Physics, APS.